In a semiconductor device manufacturing step, a film forming process is performed on a semiconductor wafer (hereinafter, referred to as “wafer”) as a substrate by ALD (Atomic Layer Deposition) using heat energy or a plasma. This film forming process may be performed by using a film forming apparatus for supplying a processing gas to a wafer mounted on a stage serving as a lower electrode from a gas shower plate provided in a processing chamber and serving as an upper electrode and generating a plasma of the processing gas between the gas shower plate and the stage.
In this apparatus, first, a raw material gas is supplied into the processing chamber and adsorbed onto the wafer. Then, a reactant gas is supplied into the processing chamber and activated by a plasma. Active species of the reactant gas and the raw material gas adsorbed onto the wafer react with each other. By repeating a cycle of alternately supplying the raw material gas and the reactant gas multiple times, a thin film having a desired film thickness is formed. In this ALD process, a film thickness profile in a wafer surface may need to be controlled.
U.S. Patent Application Publication No. 2014/0367359 discloses a technique for controlling a film thickness profile in a protruded shape in which a film thickness becomes greater at a central portion than at a peripheral portion of a wafer or in a recessed shape in which the film thickness becomes smaller at the central portion than at the peripheral portion of the wafer by controlling a plasma power or a plasma irradiation time. In this technique, the plasma power is high at a high-plasma density region. When the plasma irradiation time becomes longer, a film quality may be affected and locally changed in the wafer surface. In addition, the effect on a base film may be non-uniform in the wafer surface and damages or degree of oxidation of the base film may be non-uniform in the wafer surface.
Japanese Patent Application Publication No. 2008-244140 discloses a technique for supplying a film forming gas, an oxidizing gas and a purge gas from a central region of a gas shower plate and an oxidizing gas and a purge gas from a peripheral region of the gas shower plate in forming a film by alternately supplying the film forming gas and the oxidizing gas multiple time. In this technique, the film forming gas is supplied only from the central region of the gas shower plate and, thus, it is difficult to control a film thickness profile.
Japanese Patent Application Publication No. 2008-508744 discloses a technique related to a gas distribution injector for chemical vapor deposition reactors. The gas distribution injector has gas inlets arranged in a plurality of concentric regions and a first precursor gas and a second precursor gas having different concentrations are supplied to a central region and a peripheral region. This technique is related to CVD (chemical vapor deposition) and does not control a film thickness profile in ALD.
Japanese Patent Application Publication No. 2016-105466 discloses a shower plate for supplying a gas onto an upper surface of a substrate, the shower plate having a plurality of sectors through which the gas flows for uniformly processing the upper surface of the substrate and being applicable to ALD. However, there is not disclosed a technique for dividing a region through which gases can be separately injected into a plurality of concentric regions and controlling at least one of a raw material gas supply amount and a reactant gas supply amount in ALD to be different in the partition regions.